The study of Laguna Las Perdices, a shallow lake, involves geo-limnological, geo-environmental and corrective aspects. Geo-limnological aspects characterize the physical environment of this typical water body of the Pampean Region. Geo-environmental aspects assess natural deterioration degree along with physical-chemical and bacteriological contamination. Finally, corrective aspects contribute to the implementation of recovery measures, especially considering that Monte Municipality seeks to transform this shallow lake into a protected area. Laguna Las Perdices with 11.50 km2 is situated in the Buenos Aires Northeast region and belongs to the Lagunas Encadenadas de Monte watershed, which was evaluated by means of geolimnological methods based on cartography, aerial photography, satellite images, hydrology data and field work, i.e. leveling, bathymetry, phreatimetry, borings and sediment, soil and water sampling. Thus the physiographic, geomorphological, geological and hydrological aspects of the region and the water body were characterized The infilling sediments of the lagunas are composed of seven stratigraphic units. Those corresponding to the present accumulations are of greater interest since they are direct indicators of the environmental degradation status. The hydrological regime of the lagunas was established, according to the following parameters: rainfall on the lake surface, evaporation, runoff and groundwater flow, phreatimetry, water body-groundwater interrelationship, annual water balance and aquatic dynamics. The physical-chemical characteristics of water were established along with its ionic composition, chemical classification (according to Maucha) and the limnological category of the aquatic environment. Water and sediment determination confirmed a severe physical-chemical and bacteriological pollution which is incompatible with aquatic life and recreational use, according to the rules now in force. The pollution is due to the poor operation of the sewage treatment plant wich is currently discharging raw effluents. Thus, the laguna becomes an open-air sewer. The findings provide corrective actions of reclamation, management and conservation.